SIMION’s fast adjust feature (.PA# files) is convenient
compared to basic arrays (.PA files), in allowing electrode
potentials to be quickly changed without the relatively slow process
of refining the potential array again.
The downside, however, is that each adjustable potential involves
an additional solution array (e.g. .PA1, .PA2, etc.),
which consumes more RAM and disk space and
lengthens the Refine time. The problem is heightened if you have
dozens or hundreds of electrodes of distinct potentials, as can occur
in systems with resistor chains (common in IMS tubes and ion funnels),
as well as other systems. There is, however, a middle ground in this.
There are many cases where potentials in a system need to be quickly
adjustable, but the electrode potentials are not all completely independent.
For example, a series of 10 electrodes connected via resistors in a chain
formation will have electrode potentials that are linearly dependent and
uniquely determined if
known potentials are applied on only the two end electrodes.
In this case we only really need two solution arrays (controlled by two adjustable
potentials), or perhaps one if the potential on one end is fixed while the other may vary.

Earlier versions of SIMION (e.g. 7.0) supported a
fast (proportional) scaling solution array (.PA_ file),
which is a solution array like the others but represents
more than one electrode. The potentials of the electrodes represented
in this fast scalable set can be rescaled only proportionately to
each other during Fast Adjust.
SIMION 8.0.3 generalizes this concept further, as described below, thereby supporting
things like multiple independent resistor chains.

Note

This page is abridged from the full SIMION 8.1.1 "Supplemental Documentation" (Help file). The following additional sections can be found in the full version of this page accessible via the "Help > Supplemental Documentation" menu in SIMION 8.1.1: